Search

Food acquisition is critical for individual fitness. Recent work has highlighted the importance of behavioral traits, such as boldness, for explaining variation in foraging abilities within populations. Greater flexibility in these behavioral traits might help populations persist in the face of environmental change; this may be particularly important for small populations that are more susceptible to local extirpation. We performed a winter-feeding experiment in an extensively studied island population of Song Sparrows (Melospiza melodia) to examine if intrinsic factors (age, sex, and inbreeding) explain variation in behavioral traits (neophobia, boldness toward predators, boldness toward competitors, and aggression) and how behavioral traits influence the probability of local survival for adults and of no dispersal and survival for juveniles. Our results showed that adults were less neophobic and bolder toward competitors than juveniles. This suggests that juvenile Song Sparrows might be more vulnerable to environmental changes than adults and may help explain why juvenile survival has been more strongly impacted by a new competitor on the island. Females were less neophobic than males, indicating that the sexes vary in their behaviors associated with resource acquisition, potentially due to constraints associated with reproduction in females. We found that the individual inbreeding coefficient did not appear to influence any of the behavioral traits examined here. Lastly, more neophobic adults were found to be more likely to survive to hold a territory the following breeding season, demonstrating the consequences of behavior on future fitness. These findings highlight that behavioral traits impact resource acquisition and fitness, and, thus, variation in these behaviors may play a critical role in understanding and predicting how populations respond to environmental change. Received 25 August 2021. Accepted 26 February 2022. Key words: age, aggression, boldness, inbreeding level, neophobia, sex. La adquisicion de alimento es critica para la sobrevivencia individual. Trabajos recientes han destacado la importancia de caracteristicas conductuales, como la osadia, para explicar la variacion en capacidades de forrajeo al interior de poblaciones. Una mayor flexibilidad en caracteristicas conductuales podria ayudar a las poblaciones a persistir de cara al cambio ambiental y esto podria ser particularmente importante para poblaciones pequehas que son mas susceptibles a extinciones locales. Llevamos a cabo un experimento de alimcntacion invernal en una poblacion del gorrion Melospiza melodia que ha sido extensamente estudiada para examinar si factores intrinsecos (edad. sexo y endogamia) explican la variacion en las caracteristicas conductuales (neofobia, osadia ante depredadores, osadia ante competidores y agresion) y como las caracteristicas conductuales influencian la probabilidad de sobrevivencia local para los adultos, y la nodispersion y sobrevivencia para juveniles. Nuestros resultados muestran que los adultos fueron menos neofobicos y mas osados hacia competidores que los juveniles. Esto sugiere que los gorriones juveniles podrian ser mas vulnerables a cambios ambientales que los adultos y csto podria ayudar a explicar por que la sobrevivencia de los juveniles ha estado mas fuertemente impactada ante un nuevo competidor en la isla. Las hembras fueron menos neofobicas que los machos, indicando que los sexos varian en comportamientos asociados con adquisicion de rccursos. potencialmente debido a limitacioncs asociadas con la reproduccion en las hembras. Encontramos que el coeficiente de endogamia individual no parece influenciar ninguna de las caracteristicas conductuales que examinamos aqui. Finalmente. los adultos mas neofobicos fueron mas proclives a sobrevivir y asegurar un territorio en la siguicntc temporada reproductiva. demostrando las consecuencias del comportamiento en la sobrevivencia futura. Estos hallazgos destacan que las caracteristicas conductuales impactan la adquisicion de recursos y, por ello, la variacion en estas conductas podria jugar un papel critico en nuestro entendimiento y capacidad de predecir como responden las poblaciones al cambio ambiental. Palabras clave: agresion. edad, neofobia. nivel de endogamia, osadia, sexo., An individual's ability to obtain food resources is critical for individual fitness and can have cascading effects on a population's stability and ability to withstand changing environments (Arcese and Smith [...]

Biological responses to climate change have been widely documented across taxa and regions, but it remains unclear whether species are maintaining a good match between phenotype and environment, i.e. whether observed trait changes are adaptive. Here we reviewed 10,090 abstracts and extracted data from 71 studies reported in 58 relevant publications, to assess quantitatively whether phenotypic trait changes associated with climate change are adaptive in animals. A meta-analysis focussing on birds, the taxon best represented in our dataset, suggests that global warming has not systematically affected morphological traits, but has advanced phenological traits. We demonstrate that these advances are adaptive for some species, but imperfect as evidenced by the observed consistent selection for earlier timing. Application of a theoretical model indicates that the evolutionary load imposed by incomplete adaptive responses to ongoing climate change may already be threatening the persistence of species.

Many variables in biological research—from body size to life-history timing to environmental characteristics—are measured continuously (e.g. body mass in kilograms) but analysed as categories (e.g. large versus small), which can lower statistical power and change interpretation. We conducted a mini-review of 72 recent publications in six popular ecology, evolution and behaviour journals to quantify the prevalence of categorization. We then summarized commonly categorized metrics and simulated a dataset to demonstrate the drawbacks of categorization using common variables and realistic examples. We show that categorizing continuous variables is common (31% of publications reviewed). We also underscore that predictor variables can and should be collected and analysed continuously. Finally, we provide recommendations on how to keep variables continuous throughout the entire scientific process. Together, these pieces comprise an actionable guide to increasing statistical power and facilitating large synthesis studies by simply leaving continuous variables alone. Overcoming the pitfalls of categorizing continuous variables will allow ecologists, ethologists and evolutionary biologists to continue making trustworthy conclusions about natural processes, along with predictions about their responses to climate change and other environmental contexts. [ABSTRACT FROM AUTHOR]

This article discusses a study on the lifespans of Neotropical forest landbirds, which has been a topic of interest for scientists for a long time. The study used a 45-year dataset from central Panama to determine the longevity of 47 species. The oldest recorded individual was an 18-year-old Rufous Motmot, and most species had a lifespan of at least 7 years. The study also explored the relationship between longevity and factors such as body mass, diet, and sociality. Surprisingly, there was no correlation between body mass and longevity, and some of the smallest species actually lived the longest. The study suggests that future research should involve larger-scale studies to obtain more accurate estimates of lifespan. [Extracted from the article]

Declines in body size can be an advantageous physiological response to warming temperatures, or a result of physiological and nutritional stress. Either way, studies often assume that these climate‐induced trait changes have important implications for fitness and demography. We leveraged almost three decades of capture‐mark‐recapture data of 51 bird species in Panama to examine if body size has changed through time, how sensitive body size is to changes in weather, and if body size impacts population demography. We evaluated two metrics of body size, structural size (wing length), and body condition (residual body mass). Over the study, wing length changed in varying directions for 88% of species (23 decrease, 22 increase), but the effects were weak, and change was only significant for two species. Conversely, body condition declined for 88% of species (45), effects were stronger, and that change was significant for 22% of species (11). This suggests that nutritional stress is likely the cause of changes in body size, not an adaptive response to warming. Precipitation metrics impacted body condition across three of our four feeding guilds, while wing length was only impacted by weather metrics for two guilds. This suggests that body condition is more sensitive to change in weather metrics compared to wing length. Lastly, we found that the impact of changes in body size on survival and recruitment was variable across species, but these relationships were in the opposite direction, ultimately resulting in no change in population growth for all but one species. Thus, while different stages (adult survival and recruitment) of populations may be impacted by body size, populations appear to be buffered from changes. The lack of an effect on population growth rate suggests that populations may be more resilient to changes in body size, with implications for population persistence under expected climate change. [ABSTRACT FROM AUTHOR]

Species interactions link animal behaviour to community structure and macroecological patterns of biodiversity. One common type of trophic species interaction is disturbance foraging—the act of obtaining food at a disturbance created by another organism. Disturbance foraging is widespread across the animal kingdom, especially among birds, yet previous research has been largely anecdotal and we still lack a synthetic understanding of how this behaviour varies geographically, phylogenetically and ecologically. To address these gaps, we conducted a comprehensive literature review to test focal hypotheses about disturbance foraging behaviour in birds. We found that avian disturbance foraging was geographically ubiquitous, occurring in both aquatic and terrestrial habitats across six continents and four oceans. Consistent with predictions based on established species diversity gradients in different habitat types, the majority of terrestrial observations occurred at tropical latitudes, whereas aquatic observations took place most frequently in temperate marine waters. Although disturbance foraging was widespread across the avian phylogeny, contrary to our prediction, the behaviour was also conserved phylogenetically (Pagel's λ = 0.7) and clustered within suboscine landbirds in terrestrial environments and seabirds in aquatic environments. Similarly, although disturbers were taxonomically diverse as we predicted, interactions were unexpectedly dominated by swarm‐raiding ants in terrestrial environments and cetaceans in aquatic environments. Diet and body mass were also important predictors of disturbance foraging associations: Responders followed disturbers with similar diets and larger body sizes. Overall, our hypothesis‐testing framework provides insight into the importance of geography, phylogeny and ecology as predictors of disturbance foraging behaviour. We anticipate that this comprehensive assessment of disturbance foraging will serve to generate additional hypotheses and spark future research and management considerations about this fascinating but poorly studied suite of species interactions, especially as biotic interactions face unprecedented risks in our rapidly changing world. [ABSTRACT FROM AUTHOR]

Copyright of Ornithology (Oxford University Press) is the property of Oxford University Press / USA and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2010.06.017 Byline: Corey E. Tarwater (a), Jeffrey D. Brawn (a)(b) Abstract: Prompt natal dispersal and reproduction of offspring is viewed as the strategy to maximize lifetime reproductive success. Yet, across many species, offspring remain with their parents after independence rather than disperse. Why some species live in family groups and the behavioural mechanisms influencing the extent of family living remain unresolved. Family living is predicted to arise through slow life history traits predisposing certain lineages to family living, and then through social and ecological factors resulting in greater benefits of remaining with parents compared to dispersing. We studied family living in the western slaty-antshrike, Thamnophilus atrinucha, a bird with a slow life history, in Panama. We quantified the extent of delayed dispersal, and examined both the behavioural mechanisms influencing dispersal as well as the survival consequences. We observed that delayed dispersal increased offspring survival. Parental aggression towards offspring increased with offspring age and, in particular, when parents renested. Thus, offspring dispersed earlier when their parents renested. Fledging date and mass of offspring also influenced timing of dispersal. Although we observed higher survival of delayed dispersers, only a small proportion of offspring delayed dispersal until the next year and all dispersed to wander within other breeding pairs' territories (i.e. 'float'). Our results support theoretical predictions stating that benefits to parents from offspring retention decrease with offspring age and with renesting, leading to natal dispersal. Furthermore, we observed a reduced survival benefit of retention once offspring reached a certain age. Examining parental tolerance, the costs of floating, and how they vary with offspring age are essential to understand the costs/benefits of family living. Author Affiliation: (a) Program in Ecology, Evolution, and Conservation Biology, University of Illinois at Urbana-Champaign, U.S.A. (b) Department of Natural Resources and Environmental Sciences, University of Illinois at Urbana-Champaign, U.S.A. Article History: Received 11 September 2009; Revised 19 October 2009; Accepted 26 May 2010 Article Note: (miscellaneous) MS. number: A09-00588R

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2009.07.040 Byline: Corey E. Tarwater (a), J. Patrick Kelley (b), Jeffrey D. Brawn (a)(c) Abstract: Interactions among parents, offspring and the environment are a critical aspect of parental care. Begging by offspring usually results in increased parental provisioning. Yet, parents also vary their behaviours to reduce offspring predation. Both begging sounds and provisioning activity can increase risk of nest predation. We predicted in a high nest-predation environment, parents would satiate young and reduce begging by increasing food load but maintaining the same provisioning rates. We also assessed whether increased begging was beneficial to offspring and whether parents changed the allocation of food to particular nestlings. We increased whole-brood begging via playbacks at nests of a tropical passerine bird, the western slaty antshrike, Thamnophilus atrinucha. We observed that parents increased provisioning rates and reduced food load in response to elevated begging. Selection may therefore favour feeding hungry nestlings even when predation risk is elevated, or begging sounds may place offspring at a higher risk than increased activity. Parents reduced the time between arrival to the nest and feeding of nestlings, potentially to reduce begging sounds. Exaggerated begging did not appear to be beneficial to offspring since parents did not deliver more food. Parents switched to preferentially feed the closest offspring during the begging treatment. This suggests that, under elevated begging, parents either allowed sibling competition to influence feeding decisions, or fed the closer nestling to reduce the time between arrival to the nest and feeding. Studying species in different environments provides insight into how ecological factors such as nest predation influence parental behaviour. Author Affiliation: (a) Program in Ecology, Evolution and Conservation Biology, University of Illinois at Urbana-Champaign, U.S.A. (b) Animal Behavior Graduate Group, Department of Neurobiology, Physiology and Behavior, University of California-Davis, U.S.A. (c) Department of Natural Resources and Environmental Sciences, University of Illinois at Urbana-Champaign, U.S.A. Article History: Received 12 February 2009; Revised 14 April 2009; Accepted 30 July 2009 Article Note: (miscellaneous) MS. number: A09-00087R

Individual animal fitness can be strongly influenced by the ability to recognize habitat features which may be beneficial. Many studies focus on the effects of habitat on annual reproductive rate, even though adult survival is typically a greater influence on fitness and population growth in vertebrate species with intermediate to long lifespans. Understanding the effects of preferred habitat on individuals over the annual cycle is therefore necessary to predict its influences on individual fitness. This is particularly true in species that are resident and territorial year‐round in the temperate zone, which may face potential trade‐offs between habitat that maximizes reproduction and that which maximizes non‐breeding season (‘over‐winter’) survival. We used a 37‐year study of Song Sparrows Melospiza melodia residing territorially year‐round on a small island to examine what habitat features influenced adult over‐winter survival, how site‐specific variation in adult survival vs. annual reproductive rate influenced long‐term habitat preference, and if preferred sites on average conferred higher individual fitness. Habitat features such as area of shrub cover and exposure to intertidal coastline predicted adult over‐winter survival independent of individual age or sex, population size, or winter weather. Long‐term habitat preference (measured as occupation rate) was better predicted by site‐specific annual reproductive rate than by expected over‐winter survival, but preferred sites maximized fitness on average over the entire annual cycle,. Although adult over‐winter survival had a greater influence on population growth (λ) than did reproductive rate, the influence of reproductive rate on λ increased in preferred sites because site‐specific variation in reproductive rate was higher than variation in expected over‐winter survival. Because preferred habitats tended to have higher mean site‐specific reproductive and adult survival rates, territorial birds in this population do not appear to experience seasonal trade‐offs in preferred habitat but are predicted to incur substantial fitness costs of settling in less‐preferred sites. [ABSTRACT FROM AUTHOR]

Abstract: Studies of the phenological responses of animals to climate change typically emphasize the initiation of breeding although climatic effects on the cessation and length of the breeding period may be as or more influential of fitness. We quantified links between climate, the cessation and length of the breeding period, and individual survival and reproduction using a 34‐year study of a resident song sparrow (Melospiza melodia) population subject to dramatic variation in climate. We show that the cessation and length of the breeding period varied strongly across years, and predicted female annual fecundity but not survival. Breeding period length was more influential of fecundity than initiation or cessation of breeding alone. Warmer annual temperature and drier winters and summers predicted an earlier cessation of breeding. Population density, the date breeding was initiated, a female's history of breeding success, and the number of breeding attempts initiated previously also predicted the cessation of breeding annually, indicating that climatic, population, and individual factors may interact to affect breeding phenology. Linking climate projections to our model results suggests that females will both initiate and cease breeding earlier in the future; this will have opposite effects on individual reproductive rate because breeding earlier is expected to increase fecundity, whereas ceasing breeding earlier should reduce it. Identifying factors affecting the cessation and length of the breeding period in multiparous species may be essential to predicting individual fitness and population demography. Given a rich history of studies on the initiation of breeding in free‐living species, re‐visiting those data to estimate climatic effects on the cessation and length of breeding should improve our ability to predict the impacts of climate change on multiparous species. [ABSTRACT FROM AUTHOR]